Gripper

ABSTRACT

A gripper comprises a motor  25,  contained within a case  32,  for driving a translational nut  23  that is moved in translation, a finger  20  having one end connected to the translational nut  23,  with the other end being connected to the case  32,  in which when the one end is pulled upon a movement of the translational nut, the finger is expanded in the amount of displacement at a top end, a plate-like stopper member  26  connected to one end of the finger  20  and having a projecting piece  26   b  around the outer periphery thereof, a holder member  22  for inserting loosely the projecting piece  26   b,  a locating nut  28  for adjusting a predetermined gap from the stopper member  26  by being threadingly engaged with a threaded portion of the holder member  22,  and a spring  29  for pressing the locating nut  28.

Technical Field

[0001] The present invention relates to improvements in a gripper forgripping a minute part, and more particularly to a gripper that cansimply adjust the amount of opening or closing.

BACKGROUND ART

[0002] In International Patent WO 99/30877, the present inventordisclosed a high efficient gripper consisting of an extremely simplemechanism. Such gripper has a feature of transforming a slight amount oftranslation to an amount of bending displacement expanded tens timeslarger at a finger tip by applying a buckling phenomenon to the longcolumns of the fingers without using any special displacement expandingmechanism.

[0003] Such gripper can grip the minute part softly, and is suitable forrobot hands, for smaller and lighter.

[0004] However, there was a problem that the gripper did not vary theamount of opening or closing the fingers and was limited in the size ofa gripped object.

DISCLOSURE OF THE INVENTION

[0005] This invention has been achieved to solve the above-mentionedproblems, and it is an object of the invention to provide a gripperhaving adjustment means for adjusting the amount of opening or closingthe fingers with a simple constitution.

[0006] A first invention provides a gripper characterized by including adriving source for driving a translational portion that is moved intranslation, the driving source being contained within a case, adisplacement expanding member having one end connected to thetranslational portion, with the other end being connected to the case,in which when the one end is pulled upon a movement of the translationalportion, the displacement expanding member is extended over an amount ofthe movement from the one end and the other end, and has an expandedamount of displacement at a common top end, a plate-like stopper memberconnected to one end of the displacement expanding member and having aprojecting piece around the outer periphery thereof, a first holdermember having a cylindrical portion with a first notch for insertingloosely the projecting piece of the stopper member, and provided with athreaded portion around the outer periphery of the cylindrical portion,a locating nut for adjusting a predetermined gap from the stopper memberby being threadingly engaged with the threaded portion of the holdermember, and pressing means for pressing the locating nut.

[0007] Herein, “the driving source is contained with the case” meansthat a part or all of the driving source is contained within the case.With such gripper, the translational portion is moved until the stoppermember makes contact with the locating nut, so that the top end of thedisplacement expanding member is closed by a predetermined amount.Accordingly, there is the effect that the displacement expanding memberhas an adjustable amount of closing by making the setting of thelocating nut variable.

[0008] A second invention provides the gripper, characterized by furtherincluding a connection member having a connection portion for connectingone end of the displacement expanding member and a projection projectingin a direction against the connection portion, and the holder memberhaving a concave portion for allowing the connection member to beengaged in.

[0009] With such gripper, the displacement expanding member is connectedto the connection member, whereby there is the effect that the linkagebetween the holder member and the displacement expanding member iseasier.

[0010] A third invention provides the gripper, characterized by furtherincluding a mounting adapter member having a reference portion, with aconvex portion at one end, serving as a reference for mounting and aflange portion, and the holder member having a second notch provided ona cylindrical portion of the holder member to be engaged by a convexportion of the mounting adapter member.

[0011] With such gripper, the flange portion has the convex portionengaged in the notch of the holder member in assembling. Hence, theflange portion is securely fitted with the holder member in arotationally positional relation at any time, whereby the referenceportion of the flange portion and the displacement expanding member havea fixed positional relation at any time. Accordingly, the gripper isexchanged halfway of the work, the position of the displacementexpanding member can always maintain a predetermined relation with theworkpiece, resulting in the effect that there is no need for adjustingthe operation mechanism for the displacement expanding member.

[0012] A fourth invention provides a gripper characterized by includinga driving source for driving a translational portion that is moved intranslation, the driving source being contained within a case, adisplacement expanding member having one end connected to thetranslational portion, with the other end being connected to the case,in which when the one end is pulled upon a movement of the translationalportion, the displacement expanding member is extended over an amount ofthe movement from the one end and the other end, and has an expandedamount of displacement at a common top end, a second holder member, towhich the other end of the displacement expanding member is connected,having a cylindrical portion and a tapped hole bored in the cylindricalportion, a screw member threadingly engaging the tapped hole, and alocating member secured to the translational portion and having acontact portion making contact with the screw member.

[0013] Herein, “the driving source is contained with the case” meansthat a part or all of the driving source is contained within the case.With such gripper, the translational portion is moved forward orbackward by a predetermined amount of movement by allowing the screwmember to adjust the distance between the screw member and the contactportion of the locating member. Accordingly, there is the effect thatthe displacement expanding member has an adjustable amount of opening orclosing at the top end thereof.

[0014] A fifth invention provides the gripper, characterized in that thetapped hole including at least two holes of a first tapped hole and asecond tapped hole, and the contact portion is shaped to be almosttriangular.

[0015] With such gripper, the translational portion has a settableamount of movement by adjusting the translational position of each oftwo screw members. Accordingly, there is the effect that thedisplacement expanding member has an adjustable amount of opening orclosing at the top end thereof.

[0016] A sixth invention provides the gripper, characterized in that thestopper portion has a shock eliminating function of a ball plunger orthe like.

[0017] With such gripper, the locating arm collides with the stopperflexibly. Accordingly, there is the effect that the locating arm is lesslikely to wear.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018]FIG. 1 is a cross-sectional view showing the constitution of agripper according to one embodiment of the present invention.

[0019]FIG. 2 is a perspective view showing a finger unit of FIG. 1.

[0020]FIGS. 3A to 3D are appearance views showing a finger holder ofFIG. 1, wherein FIG. 3A is a front view, FIG. 3B is a cross-sectionalview taken along the arrow b-b, FIG. 3C is a bottom view, and FIG. 3D isa cross-sectional view taken along the arrow d-d.

[0021]FIGS. 4A and 4B show a locating plate as shown in FIG. 1, whereinFIG. 4A is a front view and FIG. 4B is a side view taken along the arrowb-b.

[0022]FIGS. 5A to 5C show a motor retainer as shown in FIG. 1, whereinFIG. 5A is a front view, FIG. 5B is a cross-sectional view taken alongthe arrow b-b and FIG. 5C is a bottom view.

[0023]FIGS. 6A and 6B show a locating nut as shown in FIG. 1, whereinFIG. 6A is a front view and FIG. 6B is a cross-sectional view takenalong the arrow b-b.

[0024]FIGS. 7A and 7B show a mounting adapter according to anotherembodiment of the invention, wherein FIG. 7A is a front view and FIG. 7Bis a cross-sectional view taken along the arrow b-b.

[0025]FIG. 8 is a cross-sectional view showing the constitution of agripper according to another embodiment of the invention.

[0026]FIGS. 9A and 9B show a locating arm as shown in FIG. 8, whereinFIG. 9A is a front view and FIG. 9B is a side view.

[0027]FIGS. 10A to 10C show a motor retainer as shown in FIG. 8, whereinFIG. 10A is a front view, FIG. 10B is a cross-sectional view taken alongthe arrow b-b and FIG. 10C is a bottom view.

[0028]FIG. 11 is a cross-sectional view taken along the arrow XI-XI inFIG. 8.

[0029]FIGS. 12A and 12B show a locating arm according to anotherembodiment of the invention, wherein FIG. 12A is a front view and FIG.12B is a side view.

[0030]FIG. 13 is a cross-sectional view of the gripper constituted ofthe locating arm as shown in FIG. 12, corresponding to FIG. 11.

[0031]FIGS. 14A and 14B show a ball plunger according to anotherembodiment of the invention, wherein FIG. 14A is a cross-sectional viewand FIG. 14B is a front view.

BEST MODE FOR CARRYING OUT THE INVENTION EMBODIMENT 1

[0032] Referring to FIGS. 1 to 6B, an embodiment of the invention willbe described below. FIG. 1 is a cross-sectional view of a gripper in theembodiment of the invention. FIG. 2 is a perspective view of a fingerunit of FIG. 1. FIGS. 3A to 3D are appearance views of a finger holderof FIG. 1. FIGS. 4A and 4B are appearance views of a locating plate ofFIG. 1. FIGS. 5A to 5C are appearance views of a motor retainer ofFIG. 1. And FIGS. 6A and 6B are appearance views of a locating nut ofFIG. 1.

[0033] In FIG. 1, the gripper includes an operation mechanism having afinger 20, a translational driving mechanism having a translationalportion for translating one end of the finger 20, and an adjustmentmechanism for adjusting the amount of closing the finger 20 with alocating nut 28. The operation mechanism is composed of a finger unit 15having the finger 20 and a finger holder 22 for securing the finger unit15.

[0034] Herein, the finger 20 has the leg portions 20 a, 20 a at theother end portion connected to a case 32, and a shared portion 20 c atone end portion connected to a translational nut 23 as the translationalportion, in which when the shared portion 20 c is pulled along with atranslational movement, the leg portions 20 a, 20 a and the sharedportion 20 c are extended more than an amount of translational movement,so that the amount of displacement between the common top ends 20 z, 20z is expanded. The finger 20 has an inverse W shape provided with twoV-character pieces shaped almost like V-character.

[0035] In FIG. 2, the finger unit 15 is composed of the finger 20, and afinger base 21 with a slit 21 a formed in the projections 21 b and 21 c,in which the leg portions 20 a and 20 b having a spring force in thefinger 20 are engaged in the notches of the finger base 21. The finger20 as a displacement expanding member is formed to release or grip aworkpiece, in which the leg portions 20 a and 20 b are formed with aslit to have a spring force, and a set tapped hole 20 d in the centralshared portion 20 c.

[0036] In FIGS. 3A to 3D, the finger holder 22 as a holder member isformed with the base retainer 22 a into which the projections 21 b and21 c of the finger unit 15 are fitted and set, two cylindrical portions22 b and 22 c internally provided, and a nut retainer 22 d with aconcave portion of square pole for engaging the translational nut 23 andhaving a rectangular cross section between a cylindrical portion 22 band a cylindrical portion 22 c, in which a threaded portion 22 e and athreaded portion 22 f are formed around the inner: and outer peripheriesof the cylindrical portion 22 c, and two first notches 22 g are formedin the central part of the cylindrical portion 22 c.

[0037] In FIG. 1, the translational nut 23 serving as a translationalportion and a connection portion is formed in the shape of a square poleto engage the nut retainer 22 d of the finger holder 22, and formed, atone end, with a columnar screw retainer 23 a having a tapped hole at thetop end, a threaded portion 23 b around the cylindrical portion, and aboss 23 c consisting of a cylindrical projection around the outerperiphery at the other end. A screw shaft 24 fixed by a screw with arotational shaft 25 a of a motor 25 as a driving source engages thethreaded portion 23 b, and the screw retainer 23 a has the finger unit15 screwed into a hole 20 d.

[0038] The translational driving mechanism includes the motor 25, amotor retainer 27 for securing a surface of the motor 25, and formedwith the threaded portions 27 d and 27 f around the outer periphery ofthe cylindrical portions 27 c and 27 a, and a cylindrical case 32 foraccommodating the motor 25 by being threadingly engaged with a threadedportion 27 f. In FIGS. 5A to 5C, the motor retainer 27 has a cylindricalportion 27 b formed with a threaded portion around the inner periphery,and an inner cylindrical portion 27 c provided at the top end and formedwith a threaded portion 27 d around the outer periphery, whereby therotational shaft 25 a of the motor 25 projects into the innercylindrical portion 27 c of the motor retainer 27 in a state where thethreaded portion 27 b of the motor retainer 27 is engaged with thethreaded portion 25 b at the top end of the motor 25. On the other hand,the threaded portion 27 d of the motor retainer 27 is engaged with thethreaded portion 22 e of the cylindrical portion 22 c for the fingerholder 22.

[0039] The adjustment mechanism includes a locating plate 26 as astopper member, the locating nut 28 threadingly engaged with thethreaded portion 22 f around the outer periphery of the finger holder22, a spring 29, a mounting adapter 30 for mounting on a robot, and aweb washer 31.

[0040] In FIGS. 4A and 4B, the locating plate 26 is formed with thestoppers 26 b, 26 b that are two projecting pieces around the outerperiphery, and has a hole 26 a in the central part. If the hole 26 a isengaged by the boss 23 c of the translational nut 23, the stoppers 26 b,26 b are inserted loosely into the notch 22 g of the finger holder 22 toproject slightly from the threaded portion 22 f formed around the outerperiphery, as shown in FIG. 1.

[0041] In FIGS. 6A and 6B, the relatively thin locating nut 28 isprovided with a ring-like arm retainer 28 a with a step at one endportion, and formed with a threaded portion 28 c around the innerperiphery to be threadingly engaged with the threaded portion 22 f ofthe finger holder 22. In FIG. 1, the mounting adapter 30 is providedwith a cylindrical boss 30 a and a flange 30 b at the other end portion,the flange 30 b being formed with a plurality of tapped holes 30 c.

[0042] In FIG. 1, the mounting adapter 30 is fitted around the outerperiphery of the motor retainer 27, with the other end being fixed viathe web washer 31 to the case 32, whereby the locating nut 28 serves asa detent owing to a compression restoring force produced by a spring 29as pressing means. Moreover, when the spring 29 and the web washer 31are compressed in a state where the case 32 is attached to the motorretainer 27 as shown in FIG. 1, an inner bottom portion of the case 32presses the other end portion of the motor 25 to an excessive extent.The spring 29 closes the finger 20 and presses the locating nut in adirection where the translational nut 23 is moved.

[0043] Referring to FIG. 1, the operation of the gripper as constitutedabove will be described below. First of all, the locating nut 28 isrotated so that a gap between the arm retainer 28 a of the locating nut28 and the locating plate 26 may be an appropriate amount by adjustingthe angle of the rotation. In this state, the translational nut 23reaches a bottom portion of the cylindrical portion fitted into the nutretainer 22 d, namely, the top end of the finger 20 shaped likeV-character is opened by a certain amount, as shown in FIG. 1. If thepower of the motor 25 is turned on in this state, the rotational shaft25 a is rotated to transmit the rotation via the screw shaft 24 to thetranslational nut 23, so that the translational nut 23 is displaced tothe right axially within the nut retainer 22 d, as shown in FIG. 1.Along with this displacement, the central shared portion 20 c of thefinger 20 is also forcefully displaced in the same direction. Thereby,the finger 20 is subjected to a bending moment, and bent about ten timeslarger than a displacement of the translational nut 23 in a directionwhere the top end is closed. On the other hand, if the rotation of themotor 25 is reversed, the central shared portion 20 c of the finger 20is returned to the left axially, so that the finger 20 is also restoredto its original state as shown in FIG. 1.

[0044] In the case where the closing amount of the finger 20 is notappropriate, the locating nut 28 is rotated in this state to adjust itsposition. By repeating the above operation, the locating nut 28 isrotated to have a predetermined closing amount of the finger 20 and setat that position.

[0045] As described above, the gripper allows the adjustment for theposition of the locating plate 26 fitted with the translational nut 23by rotating the locating nut 28. Accordingly, the central shared portion20 c of the finger 20 is displaced (pulled) a predetermined amount tothe right in the axial direction by the translation nut 23, so that thetop end of the finger 20 is displaced more than the predetermined amountin the closing direction. Accordingly, it is possible to provide thegripper capable of adjusting the closing amount of the finger 20 inaccordance with the size of workpiece or a gripping force.

EMBODIMENT 2

[0046] Referring to FIGS. 7A and 7B, an embodiment of the invention willbe described below. FIGS. 7A and 7B are appearance views of a mountingadapter in the embodiment of the invention. In the embodiment 2, themounting adapter 60 as shown in FIGS. 7A and 7B is employed, instead ofthe mounting adapter 30 in the embodiment 1.

[0047] In FIGS. 7A and 7B, the mounting adapter 60 is formed with acylindrical boss 60 a, a flange 60 b provided at the other end portion,a plurality of tapped holes 60 c serving as the reference in attachingthe gripper to the flange 60 b, and a projection 60 d as a convexportion to be fitted in a second notch 22 g of the finger holder 22 atan end portion of the boss 60 a. The constitution and operation of anoperation mechanism and a driving mechanism are the same as in theembodiment 1.

[0048] Referring to FIGS. 1, 3A to 3D, 7A and 7B, the operation of theabove gripper will be described below. In assembling the gripper, themounting adapter 60 has the projection 60 d fitted into the notch 22 gof the finger holder 22 so that the tapped holes 60 c are always placedat a predetermined rotational position with respect to the finger 20.

[0049] Accordingly, even if the gripper is exchanged due to its expiredlife, the finger 20 is retained at a certain positional relation to theworkpiece before and after the exchange, whereby there is no need foradjusting the operation mechanism for the finger 20 even if the gripperis exchanged.

EMBODIMENT 3

[0050] Referring to FIGS. 8 to 11, an embodiment of the invention willbe described below. FIG. 8 is a cross-sectional view showing the entireconstitution of a gripper, corresponding to FIG. 1 in the embodiment 1.In FIG. 8, the mounting adapter 30 and the case 32 are omitted, becausethey are unnecessary for the explanation. Particularly in the embodiment3, the case 32 containing the entire motor 25 can be omitted.

[0051] This embodiment employs a finger holder 41, a motor retainer(case in claim 4) 43 and a locating arm 40, instead of the finger holder22, the motor retainer 27 and the locating plate 26 in the embodiment 1.

[0052] The gripper includes the motor retainer 43 for receiving an endportion of the motor 25, the finger holder 41 for holding a cylindricalperipheral end portion of the motor retainer 43 by being fixed by ascrew 43 a, the locating arm 40 being fitted through the rotationalshaft 25 a of the motor 25, and a stopper 42 as a screw member composedof a set screw engaged around the outer periphery of the other endportion of the finger holder 41. The finger holder 41 has an innercylindrical portion 41 a for accommodating the translational nut 23 anda nut retainer 41 b on the bottom portion behind the inner cylindricalportion 41 a.

[0053] In FIGS. 9A and 9B, the locating arm 40 as a locating member hasan arm 40 a as a projecting contact portion, and a circular portionformed with a hole 40 b shaped similarly to the rotational shaft 25 a tobe fitted through the rotational shaft 25 a of the motor 25. In FIGS.10A to 10C, the motor retainer 43 is formed with the holes 43 b, 43 bfor passing a threaded portion of the screw 43 a on the cylindricalportion at the end portion, and a tapped hole 43 c for engaging thestopper 42 as the screw member.

[0054] Referring to FIGS. 8 and 11, the operation of the gripper asconstituted above will be described below. In FIG. 8, like FIG. 1, thetranslational nut 23 reaches a bottom portion of the cylindrical portionfitted into the nut retainer 41 b, in which the tip end of the finger 20is opened by a certain amount.

[0055] If the power of the motor 25 is turned on in this state, thelocating arm 40 is rotated from the position of the solid line to theposition of the broken line as indicated in FIG. 11, along with therotation of the rotational shaft 25 a of the motor 25, until the arm 40a makes contact with the stopper 42, while the translational nut 23 isdisplaced within the nut retainer 41 b to the right axially as indicatedin FIG. 8, so that the finger 20 is closed by the same operation of theembodiment 1.

[0056] On the other hand, if the motor 25 is reversely rotated, thetranslational nut 23 is displaced to make contact with an inner bottomface of the nut retainer 41 b, and the finger 20 is restored to thestate of FIG. 8.

[0057] In the case where the closing amount of the finger 20 isincreased, if the stopper 42 is rotated backward by a driver, thelocating arm 40 has an increased amount of rotation in a directiontoward the broken line, so that the central shared portion 20 c of thefinger 20 is more forcefully displaced. Accordingly, the finger 20 islargely closed.

EMBODIMENT 4

[0058] Referring to FIGS. 12A, 12B and 13, an embodiment of theinvention will be described below. FIG. 13 is a cross-sectional viewlike FIG. 11. A gripper of this embodiment employs a locating arm 50,instead of the locating arm 40 of the embodiment 3.

[0059] In FIGS. 12A, 12B and 13, the locating arm 50 is triangular, andformed with three arms 50 a, 50 a and 50 a as the contact portion and ahole 50 b for fitting the rotational shaft 25 a of the motor 25 in thecenter. A motor retainer 53 is formed with a cylindrical portion at anend portion, the cylindrical portion being formed with the first andsecond tapped holes 53 c, 53 c for engaging the stoppers 52 a, 52 b asthe first and second screw members having a threaded portion.

[0060] In FIG. 13, the locating arm 50 is securely fitted through therotational shaft 25 a of the motor 25, and has two stoppers 52 a and 52b, opposed to the sides of a triangle, which are attached around theouter periphery of the finger holder 51 at the other end portion.

[0061] Referring to FIG. 13, the operation of the gripper as constitutedabove will be described below. The operation is roughly the same as inthe embodiment 3. That is, the locating arm 50 is rotated from theposition of the solid line to the position of the broken line asindicated in FIG. 13, along with the rotation of the motor 25, until thearm 50 a of the locating arm 50 makes contact with the stopper 52 a.

[0062] On the other hand, if the motor 25 is reversely rotated, thelocating arm 50 is rotated back from the position of the broken line tothe position of the solid line, until the arm 50 a makes contact withthe stopper 52 b.

[0063] And two stoppers 52 a and 52 b can adjust the projecting amountindependently of each other, and thereby adjust the opening and closingamount of the finger 20.

[0064] It is needless to say that the gripper has a bottom portion ofthe cylindrical portion fitted into the nut retainer 41 b formedslightly deeper than the locating arm 50 leads to the stopper 52 a.

EMBODIMENT 5

[0065] Referring to FIGS. 14A and 14B, an embodiment of the inventionwill be described below. The embodiment has a feature of using the ballplungers 70 a and 70 b as shown in FIGS. 14A and 14B, instead of twostoppers 52 a and 52 b in FIG. 13. The ball plungers 70 a and 70 b havea function of flexibly stopping a moving object by absorbing a kineticenergy of the moving object. Therefore, a spring 70 c is containedwithin the screw in a compressed state, and a ball 70 d is fitted via aspacer at a contact portion with a movable portion.

[0066] Accordingly, if the locating arm 50 is rotated in a directionfrom the position of the solid line to the position of the broken lineor its opposite direction, along with the rotation of the motor 25, itis rotated until the arm 50 a of the locating arm 50 makes contact withthe ball plungers 70 a and 70 b, as shown in FIG. 13. By this contact,the arm 50 a of the locating arm 50 collides with the ball plungers 70a, 70 b at a rotation rate of the locating arm 50, but the ball 70 d isdisplaced momentarily via the spring 70 c to damp a striking energy.

INDUSTRIAL APPLICABILITY

[0067] As described above, this invention is suitable for the uses ofthe gripper.

1. A gripper characterized by comprising: a driving source for driving atranslational portion that is moved in translation, said driving sourcebeing contained within a case; a displacement expanding member havingone end connected to said translational portion, with the other endbeing connected to said case, in which when said one end is pulled upona movement of said translational portion, said displacement expandingmember is extended over an amount of said movement from said one end andthe other end, and has an expanded amount of displacement at a commontop end; a plate-like stopper member connected to one end of saiddisplacement expanding member and having a projecting piece around theouter periphery thereof; a first holder member having a cylindricalportion with a first notch for inserting loosely the projecting piece ofsaid stopper member, and provided with a threaded portion around theouter periphery of said cylindrical portion; a locating nut foradjusting a predetermined gap from said stopper member by beingthreadingly engaged with said threaded portion of said holder member;and pressing means for pressing said locating nut.
 2. The gripperaccording to claim 1, characterized by further comprising a connectionmember having a connection portion for connecting one end of saiddisplacement expanding member and a projection projecting in a directionagainst said connection portion, and said holder member having a concaveportion for allowing said connection member to be engaged in.
 3. Thegripper according to claim 1 or 2, characterized by further comprising amounting adapter member having a reference portion, with a convexportion at one end, serving as a reference for mounting and a flangeportion, and said holder member having a second notch provided on acylindrical portion of said holder member to be engaged by a convexportion of said mounting adapter member.
 4. A gripper characterized bycomprising: a driving source for driving a translational portion that ismoved in translation, said driving source being contained within a case;a displacement expanding member having one end connected to saidtranslational portion, with the other end being connected to said case,in which when said one end is pulled upon a movement of saidtranslational portion, said displacement expanding member is extendedover an amount of said movement from said one end and the other end, andhas an expanded amount of displacement at a common top end; a secondholder member, to which the other end of said displacement expandingmember is connected, having a cylindrical portion and a tapped holebored in said cylindrical portion; a screw member threadingly engagingsaid tapped hole; and a locating member secured to said translationalportion and having a contact portion making contact with said screwmember.
 5. The gripper according to claim 4, characterized in that saidcontact portion is shaped as a triangle, said tapped hole comprising atleast two holes of a first tapped hole and a second tapped hole, saidscrew member has a first screw member and a second screw member, inwhich said first screw member and said second screw member make contactwith different sides of said triangle.
 6. The gripper according to claim4 or 5, characterized in that said screw member has a shock eliminatingfunction for absorbing a columnar shock on said screw member at a topend.